Starbucks vows to phase out eggs from caged chickens as well as pork products from animals raised in cramped gestation cages, and will ask suppliers to abandon artificial growth hormones and certain other practices.

Starbucks, in a major revamp to its animal-welfare policy, has vowed to phase out buying eggs laid by hens tightly packed for life in crowded cages and pork products from farms that use gestation crates.

The company will also push its suppliers to abandon artificial growth hormones and fast-growth practices for poultry, as well as other animal-raising techniques considered by some consumers to be inhumane, such as dehorning, tail docking and castration.

Starbucks also wants to offer chicken products from birds slaughtered in humane ways.

The new mandate is “the most comprehensive animal-welfare policy of any national restaurant chain,” said Wayne Pacelle, president of the Humane Society of the United States, a nonprofit that focuses on the humane treatment of animals and advised Starbucks on the new policy.

The Seattle-based coffee giant didn’t say when it would start offering cage-free eggs and avoiding pork from farms that confine their breeding pigs in stifling gestation crates where they can barely move.

But the new policy posted on its website states that the company is working with the industry “on creating reasonable time frames.”

The move replaces its previous policy, which was simply a preference for purchasing cage-free eggs and other food produced with methods favored by animal-rights activists.

Starbucks’ decision to step up pressure on animal-product suppliers comes at a time when the company is ramping up its food offerings, counting on them to provide a large chunk of its growth over the next five years.

The Humane Society’s Pacelle wrote in a blog post that part of what gives Starbucks’ new cage-free policy such impact is that it includes not only eggs in a shell, but also in liquid form, which it buys in great quantity to make pastries.

Also significant is the fact that Starbucks wants to apply these new standards not only in the U.S., but in its rapidly expanding international operations as well.

The move coincides with California laws taking effect Jan. 1 that mandate cage-free production and sale of eggs within the state. Starbucks has more than 2,600 stores in California, about a fifth of its U.S. total.

Starbucks’ decision and its reluctance to specify a time frame raise the question of whether there will be enough available eggs and meat products to support the coffee giant’s buying under the new policy.

But Josh Balk, food-policy director at the Humane Society, said in an interview that Starbucks’ gradual approach to farm products puts it on a “sustainable direction.”

Other big corporations have also sought to influence farms to adopt more humane standards. Consumer-brands giant Unilever, which owns Ben & Jerry’s and Hellmann’s mayonnaise, among others, has also vowed to move to 100 percent cage-free eggs. As of the end of 2013, 40 percent of its eggs were cage-free.

According to Balk, all of Costco’s Kirkland Brand eggs are cage-free and the company has promised to phase out suppliers that use gestation crates by 2020. Burger King will adopt exclusively cage-free eggs by 2017, he said.

But Balk added that Starbucks’ policy is unusually broad, addressing a wide range of issues. “It’s extensive,” he said. “That is going to affect a whole lot of animals.”

Balk said that about 10 percent of the eggs produced in the U.S. come from a cage-free environment, up from about 1 percent a decade ago.

Likewise, while five years ago nearly all breeding sows were kept in gestation cages where they can hardly move, now only about 80 percent are, and that percentage “is continuously going down as these policies start to phase in,” he said.